Needle-free injection systems provide an alternative to standard fluid delivery systems, which typically use a needle adapted to penetrate the outer surface of a target. Typically, needle-free injection systems are designed to eject the fluid from a fluid chamber with sufficient pressure to allow the fluid to penetrate the target to the desired degree. For example, common applications for needle-free injection systems include delivering intradermal, subcutaneous, and intramuscular injections into or through a recipient's skin. For each of these applications, the fluid must be ejected from the system with sufficient pressure to allow the fluid to penetrate the tough exterior dermal layers of the recipient's skin.
Examples of needle-free injection systems are found in U.S. Pat. Nos. 4,940,460, 4,941,880, 5,399,163, 5,746,714, 5,782,802, 5,993,412, 6,096,002, 6,132,395, 6,264,629, 6,383,168, 6,471,669, 6,572,581, 6,585,685, 6,607,510, 6,641,554, 6,645,170, 6,648,850, 6,676,630, 6,689,093, 6,752,781, and 6,783,509, the disclosures of which are incorporated herein by reference for all purposes.
Since needle-free injection systems require the production of high fluid pressures, recoil of injector components may limit device accuracy or effectiveness. Various attempts have therefore been made to reduce recoil in injection systems. Examples of such devices are found in U.S. Pat. No. 5,957,886 and U.S. Patent Application Nos. 2004/0106895 and 2005/0267403, the disclosures of which are incorporated herein by reference for all purposes.